"Slow down." "Use caution." Drivers know these are words to live by during rain, sleet or snow. But such rules of thumb aren't always helpful when you're on the road, says Erik Nelson, a graduate student in the human factors and applied cognition program at George Mason University in Fairfax, Va.
Most drivers aren't sure how much they should reduce their speed when roads are wet, and speed limits — which are set for ideal driving conditions — offer little guidance. The amount of precipitation on a road can also change from minute to minute, quickly creating hazardous conditions. "There are a lot of crashes that occur after it has stopped raining and roads are still wet because people get this false sense of security," says Nelson.
To give drivers more specific guidance in bad weather, Nelson and four other George Mason University human factors students invented a speedometer that offers constantly updated speed recommendations using information from windshield wipers, temperature gauges and wheel traction sensors. Their "Speed Limits for Inclement Conditions," or SLIC, was a North American finalist chosen to compete in the international student design competition at the 2009 Enhanced Safety of Vehicles conference. Now, its creators are patenting their idea and hope that in the not-too-distant future the tool will be a standard car feature.
"SLIC is very well-timed," says Chris Monk, PhD, of the Federal Highway Administration's Office of Safety, Research and Development and the group's former adviser. "It's consistent with a lot of activity that's going on now in the area of intelligent transportation to try to give drivers more information and feedback about their performance."
No Need for Speed
SLIC was born when Nelson and his cohorts — Jane Barrow, Daniel Roberts, David Cades, PhD (now a scientist at Exponent), and David Kidd, PhD (now a research scientist at the Insurance Institute for Highway Safety) — started digging into U.S. automobile crash data. They found that one-quarter of U.S. traffic crashes happen during bad weather and approximately 7,400 people are killed each year in weather-related traffic crashes, according to the Federal Highway Administration.
Those sobering statistics gave the students an idea: What if they could reduce that number?
Drawing on their human factors training, the team produced several variations of a design for a weather-sensitive speedometer that they tested with 30 participants, each using a video-game-like device with a steering wheel that simulated a drive along a country road with occasional stretches of inclement weather. In their study, the speedometer came onscreen whenever the driver encountered bad weather or other poor driving conditions, such as a gravel road. The team also used colors to alert drivers. The SLIC's speed ranges glow red and yellow, indicating a suggested speed based on the current road and weather conditions.
In addition, an icon with the word "speed" and two down arrows appears in the speedometer's upper right corner until road conditions improve. Their research showed that this icon was easier for people to follow than a message saying "Slow down" or showing pictures of snow or rain next to the speedometer, says Nelson.
Without training, drivers quickly picked up how the tool worked and slowed down when the speedometer activated onscreen.
"When you're driving, you can't afford to look at some complex display to understand that you should be driving 37 mph," says Nelson. "You need to be able to glance at something and have it be intuitive."
Much of the technology that could support SLIC in vehicles is already available, says Barrow.
"There are now temperature sensors that can tell what kind of moisture is in the air, like fog, and there are optical sensors that can tell if there's standing water in the road," she says.
Other features that could inform SLIC include sensors that measure the amount of water on the windshield and navigation software that tracks speed limits on various roads, Barrow says.
Ideally, SLIC would integrate that information to help a driver pick an appropriate speed and avoid an accident, she says.
The team is also counting on the fact that many auto manufacturers are moving toward liquid crystal display (LCD) dashboards, which could make overlaying SLIC on the car's existing speedometer as simple as a software tweak.
"The automobile manufacturing industry is always looking for ways they can improve their product, and SLIC would be fairly low-cost to implement," adds Monk.
Their patent will take at least an additional two years to process, but the students have already collaborated with graduate students from the George Mason business school to devise the best marketing plan. Automobile manufacturers have traditionally outsourced the engineering of their speedometers, but automakers may start producing their own as LCD dashboards become standard, says David Grossman, JD, assistant director of George Mason's Office of Technology Transfer, who filed the team's patent application. Grossman, an electrical engineer turned patent lawyer, has confidence in SLIC's potential.
"Getting a patent is expensive. We don't follow through unless we think there is a good chance something will actually happen," says Grossman, adding that "most of our technology disclosures come from hard engineering departments or biological research, and it's great to see one coming from psychology."